1. Field of the Invention
The present invention relates to a focus adjusting system, and in particular relates to a camera having a contrast-detection type focus adjusting system.
2. Description of the Prior Art
A conventional digital camera with a contrast-detection type focus adjusting system (focusing system) which detects a focus state by performing an AF search operation in which a focusing lens group is moved from one to the other of the infinite focus position (far extremity/position for bringing an object at infinity into focus) and the closest (shortest) focus position (near extremity/position for bringing an object at the shortest distance in working range into focus) is known in the art, wherein the AF search operation is terminated upon a peak contrast occurring during the AF search operation on the supposition that this position of the focusing lens group at which the peak contrast is obtained is an in-focus position. This digital camera is disclosed in Japanese Unexamined Patent Publication 2002-311325. In this digital camera, the aforementioned AF search operation commences upon the release bottom of the camera being depressed in a half way at normal times. Moreover, a digital camera is disclosed in Japanese Unexamined Patent Publication 2002-072074, wherein the AF search operation starts from the infinite focus position when the focusing lens group is positioned closer to the infinite focus position than the closest focus position, and starts from the closest focus position when the focusing lens group is positioned closer to the closest focus position than the infinite focus position, in order to reduce the time for the AF search operation.
Furthermore, among conventional cameras having a shake reduction system (camera-shake reduction system/camera-shake correcting system/image stabilizer), a camera is known in the art in which it is detected which of the following three different states the camera is currently in according to the output of a gyro sensor: a first state in which the camera is being swung for panning, a second state in which the camera is being swung for tilting, and a third state in which the camera is being shaken due to hand shake or the like, and in which an autofocusing operation is performed when it is detected that the camera is currently in the aforementioned first or second state. This camera is disclosed in Japanese Unexamined Patent Publication H06-153053.
However, in conventional digital cameras, even if the release button is again depressed half way with a main object substantially remaining unchanged after focus is achieved (an in-focus state is obtained) on the main object by the AF search operation, the AF search operation in which the focusing lens group is moved from the infinite focus position or the closest focus position is performed again, and accordingly, it sometimes takes time for the AF search operation to be performed when it is performed for a searching range in which no main object exists.